The present invention relates to a setting device for a feed device of an internal combustion engine, wherein the feed device provides control of the speed of rotation upon idling, is connected to an adjusting rod, and is pretensioned by a return spring. The feed device includes a first adjustable stop and a second fixed stop operable with an actuating lever of the feed device, the second fixed stop limiting a range of adjustment of the first stop for a minimum setting of the feed device.
In order to reduce the consumption of fuel and thus the amount of the exhaust and the emission of noise, it is known to adjust the idling speed of an internal combustion engine at the lower limit of the value required for smooth operation. This minimum value, however, varies greatly with various operating conditions; for instance after a cold start in the winter or upon an added load, such as air conditioning or hydraulic power assistance, it is much larger than in the case of a warmed-up engine without load. If a stop of the feed device, i.e. of the throttle valve or the control rod an injection pump, determines the idling speed, then the adjustment range of this stop must be correspondingly large in order to satisfy the control requirements for all operating conditions which may occur. It is desirable or even necessary for reasons of safety that the idling control be reduced to the smallest possible value upon a failure or an error in control in order reliably to avoid dangerous operating conditions due to an excessively high idling speed of rotation which can lead to forward movement of the vehicle. Upon an operating condition of the internal combustion engine which would, in principle, require an increase in the idling speed, the displacement of the idling stop to the minimum value however leads to rough idling or stalling, so that it is extremely difficult to move at all a vehicle the idling control of which has failed. There is thus a demand for setting devices which still permit emergency travel with a sufficient idling speed after failure of the idling control.